In order to ensure that a micro speaker module can work normally in different air pressure environments, a pressure relief device is generally arranged in the rear sound chamber of a speaker to maintain the air pressure equilibrium between the rear sound chamber and the external environment.
The existing pressure relief device is generally designed as follows: a pressure relief hole is provided on a position, where the rear sound chamber is located, of the housing, and, as the material of the housing generally uses plastics, the diameter of the pressure relief hole is usually greater than 0.1 mm due to the material limitation. A large size of the pressure relief hole is not good for the speaker's acoustic seal. Besides, a pressure relief groove with a gland affixed on it must be disposed on the housing on the side close to the rear sound chamber. The pressure relief groove communicates with the pressure relief hole to form a pressure relief passage, which not only can equilibrate the pressure between the rear sound chamber and the external environment, but also can achieve a technical effect of acoustic seal. In this structure, the pressure relief device is composed of a pressure relief hole, a pressure relief groove, a gland, and a mesh. For the pressure relief device, the structure is complicated, the processing is difficult and the yield rate is low.